1. Field of the Invention
This invention relates to a signal discriminator utilized as a device for preventing noise emitted from wirings inside and outside of electronic devices.
This invention relates to a signal discriminator for absorbing noise transmitted from electronic devices or introduced into the electronic devices through a cable and discriminating necessary signals, utilizing a magnetic core having a closed magnetic path composed of divided magnetic cores divided in a plural number.
This invention relates to a signal discriminator utilized as a device for preventing noise in electronic devices.
2. Discussion of the Background
FIG. 5 shows an as attached appearance perspective view of a first conventional example of a signal discriminator. In FIG. 5, reference numerals 1 and 1A designate cases made of a synthetic resin capable of opening and closing, 2 and 2A, two sets of dual divided magnetic cores respectively having different characteristics, and 11, a wire attached to the signal discriminators 10 and 10A.
In the above construction, a composite effect in noise attenuation is obtained as shown in a noise attenuation characteristic diagram of FIG. 4 by utilizing the magnetic cores 2 and 2A having different characteristics. Assuming that the magnetic core 2 is provided with the noise attenuation characteristic as shown by a curve X in FIG. 4, and the magnetic core 2A is provided with the noise attenuation characteristic as shown by a curve Y, the composite noise attenuation characteristic synthetically becomes as shown in a curve Z in the arrangement of the magnetic cores 2 and 2A in FIG. 5, which can handle a wide band noise.
In the first conventional system, as stated above, a plurality of signal discriminators should be provided respectively and separately on the same wire corresponding with the wide band noise. Accordingly, attaching and handling thereof are complex and take much time and labor. Furthermore, the attached portions become long which is a disadvantage in appearance.
On the other hand, the signal discriminator is generally used as an electric noise absorbing member for preventing electromagnetic noise hazard.
FIG. 12 is a sectional diagram showing a second conventional signal discriminator as shown, for instance, in Japanese Unexamined Patent Publication No. 172197/1987, Japanese Unexamined Patent Publication No. 115/1990 and the like. In FIG. 12, a reference numeral 101 designates a signal discriminator, attached to an attaching hole 103 of a panel 102 and a cable 105 passes through a hole 104 thereof. The signal discriminator 101 is composed of a ring-like main body of the signal discriminator 106 attached to the attaching hole 103, a ring-like magnetic core 107 incorporated in the main body of the signal discriminator 106, and a ring-like fixing member 110 attached to the periphery of an inserting portion 109 so that it interposes the panel 102 between a flange 108 of the main body of the signal discriminator 106 and it.
In the signal discriminator 101 the main body of the signal discriminator 106 is attached to the attaching hole 103 of the panel 102, in a state wherein the cable 105 passes through an inner hole 104 of the main body of the signal discriminator 106. The ring-like fixing member 110 is attached and secured by an adhesive, to the outer periphery of the inserting portion 109. In the signal discriminator 101 attached as above, the magnetic core 107 absorbs noise flowing in the cable 105 and discriminates necessary signals.
In the above conventional signal discriminator 101, it is necessary to arrange the main body of the signal discriminator 106 and the ring-like fixing member 110 previously at both sides of the panel 102, and passes the cable 105 therethrough. Accordingly, at every time for exchanging the magnetic core 107, it becomes necessary to remove the cable 105.
Furthermore, in Japanese Unexamined Utility Model Publication No. 91315/1990, a signal discriminator is proposed wherein divided magnetic cores divided in a plural number are accommodated in a case capable of opening and closing thereof composed of divided cases and which is attached to a cable by integrating it so as to surround the outer peripheral portion of the cable.
However, in such a signal discriminator, a means for fixing the signal discriminator to the cable, is necessary and a bush is separately necessary for a cable penetrating portion of a panel.
FIGS. 18 through 21 are respectively perspective construction views of a third through a sixth conventional signal discriminator which are generally and widely in use. In FIG. 18, a reference numeral 201 designates a case made of a synthetic resin capable of opening and closing and having a latch mechanism, 202, a square magnetic core (hereinafter, core) divided in two, 210, a signal discriminator, and 211, a cable. In FIGS. 19 through 21, reference numeral 212 designates a synthetic resin mold inserted with a sleeve-like core 220 or sleeve-like cores 220a and 220b having different characteristics, and 213, a thermally contractive tube covering cores 220a and 220b.
The above constructed signal discriminators are utilize to prevent noise emitted from wirings inside and outside of electronic devices. Generally, when it is mounted in a later step, the case system capable of opening and closing as shown in FIG. 18 is adopted. Furthermore, when it is mounted in an early step, the integrally forming system of FIG. 19 is adopted.
Furthermore, to promote the signal discriminating effect, a plurality of magnetic cores having different characteristics (or the same characteristic), for instance two magnetic cores 220a and 220b shown in FIGS. 20 and 21, are utilized, and the integrated forming of FIG. 20 or the simplified forming system which performs the forming by the thermally contractive tube of FIG. 21, is in use.
Since the third through the sixth conventional signal discriminators are composed as above, the case system capable of opening and closing and mountable in a later step is low in commercial value thereof with respect to the shape. Specifically, the integrated forming system is devoid of attachability and detachability, requires time, labor, and equipment in forming thereof, the longitudinal dimension thereof is elongated with respect to the shape, which induces lowering of the signal discriminating efficiency. Furthermore, in the system utilizing a plurality of magnetic cores, there are various problems associated with formation, the commercial value, and the handling thereof.